Natural gas may be used as a fuel source for trains. Natural gas is an attractive alternative to diesel fuel because it can be less expensive to produce and procure, while producing less carbon dioxide when combusted. Natural gas is readily available as a fossil fuel and can also be produced from waste at man-made facilities.
Traditional locomotives, including natural gas-fueled locomotives, combust fuel to provide a tractive force used to pull or push one or more railroad cars. Such locomotives travel across varying terrain that may include one or more upward grades. On grade, the locomotive must pull or push the railroad cars with a force that is greater than the force required to move the railroad cars on flat sections of the railroad line. Traditional locomotives lack the power and responsiveness needed to maintain speed over such grades, thereby reducing throughput on the railroad line and decreasing profitability. Traditional locomotives also generate emissions that may exceed accepted limits (e.g., limits imposed by cities, limits imposed by government agencies, etc.), thereby resulting in payment of emissions penalties.